(PHP 4 >= 4.2.0, PHP 5 <= 5.1.2) Create a session

(PHP 4 >= 4.2.0, PHP 5 <= 5.1.2) Set value in session

(PHP 4 >= 4.2.0, PHP 5 <= 5.1.2) Get value from session

(PHP 4 >= 4.3.2, PHP 5, PHP 7) Update the current session id with a newly generated one